Parliament's portfolio committee on police approved draft legislation on Wednesday to restructure the Hawks after amending it to make the elite unit answer to the minister, not the national commissioner.

The last minute change was brought on the advice of parliamentary law advisers, who said keeping the unit under the command of the commissioner would leave the bill vulnerable to another Constitutional Court challenge if it became law.

The bill, an amendment to the SA Police Service Act, was drafted in response to the court's landmark Glenister ruling last year that found the Hawks or Directorate for Priority Crime Investigation (DPCI) unit was not sufficiently independent.

"The issue of the reporting line of the head of the directorate has not been clarified. The national commissioner could claim that the head should report to him or her," legal adviser Nthuthuzelo Vanara said of the earlier version.

"It would compromise the structural independence of the head of the DPCI."

The bill was then changed to state explicitly that the head of the Hawks would report to the police minister.

The issue was repeatedly raised in public hearings on the bill last month.

Legal and security experts warned that the unit would not be seen as independent if it answered to the commissioner – essentially a political appointment.

All political parties voted in favour of the final version, with the exception of the Democratic Alliance. DA MP Dianne Kohler-Barnard said she needed to consult further with her party.

Committee chairwoman Sindi Chikunga said the bill would be debated by the National Assembly on May 23.

She said she was convinced that the bill would pass constitutional muster.

"I'm not scared of anybody taking us to the Constitutional Court. And even if they did, it will assist us in now for once and all having a bill that has passed the court test."

Other last-minute changes made to the bill on Wednesday included amendments to give the members of the elite corruption fighting unit greater security of tenure.

The head of the Hawks will now be appointed for a term of between seven and 10 years. He can no longer be suspended without pay and suspension has to be followed by an inquiry headed by a sitting or retired judge.

The committee also reduced the role of the ministerial and operational oversight committee – seen as allowing room for political meddling – and gave some of these functions to the minister.

In a change requested by Hawks director Anwa Dramat, the bill states that the unit may request assistance from crime intelligence for a designated period.

The ANC said this clause clearly limited the duration and nature of the assistance.

MP Anneliese van Wyk said this was vital because one of the reasons for the controversial disbanding of the unit's predecessor, the Scorpions, was that it had illegally established an intelligence capacity.

The police secretariat told MPs the final version of the bill successfully ring-fenced the operations and the budget of the Hawks to comply with the judgment.

The minister has to intervene if there is a dispute between the unit and the commissioner about expenditure.

Kohler-Barnard said there was still scope for the commissioner to meddle in operational decisions. "Who prevails if there is a dispute between the national commissioner and the DPCI on whether to investigate?" she asked.

Police secretary Jenny Irish-Qhobosheane replied that the bill allowed the head of the Hawks to hand any case referred to the unit back to a provincial police commissioner, who then had to investigate it.

She stressed that refusing to do so would be a crime.

Kohler-Barnard remained unconvinced. She argued that ultimately provincial commissioners would do the national commissioner's bidding.